# API version dropped while old app live: first 30 minutes checklist

Source: https://releasefailures.com/incidents/api-version-dropped-while-old-app-live/
Content version: 1.0.0
Verified on: 2026-10-21
Licence: CC BY 4.0

Definition: The backend removes an API version still used by installed app versions.
- [ ] FM-01 Group new errors and support tickets by client version and API version to confirm the failures come from old pinned versions.
- [ ] FM-02 Check whether a scheduled API version retirement or deprecation took effect at the start time, with no application deploy.
- [ ] FM-03 Search API logs for HTTP 410 responses stating that the requested API version is no longer available.
- [ ] FM-04 Decide whether to extend the end-of-life date through a configuration change or to restore the old endpoints temporarily.
- [ ] FM-05 Tell customers that failed operations can be retried once compatibility is restored.
- [ ] FM-06 Post a status update that names the affected API versions, the affected client versions and the new cut-off date.
- [ ] FM-07 Publish the minimum client versions customers must upgrade to before the new cut-off date.